1. Field of the Invention
The present invention relates to an integrated IP (Internet Protocol) network of an IP network for computer communication based on the TCP/IP (Transmission Control Protocol/Internet Protocol) technology.
2. Description of the Related Art
The IP network designed to send and receive digitized voice data according to the TCP/IP technology (hereinafter referred to as an “IP telephone network”) uses a communication circuit speed of about 64 Kbps to keep the arrival time of voice data below, for example, 0.1 second. An IP telephone network to send and receive a compressed video image of TV according to the TCP/IP technology (hereinafter referred to as an “IP video network”) uses a communication circuit speed of, for example, 1.5 Mbps and allows a video data arrival time of a few minutes.
The IP telephone network to transfer texts of electronic vouchers according to the TCP/IP technology (hereinafter referred to as an “IP electronic text network”) has a communication circuit speed of about 128 Kbps to keep the data arrival time less than 1 second. In this case, because the reliability is given a greater importance than those of voice transmission and TV video transmission, the communication error occurrence rate is kept less than one one-hundredth those of the IP telephone network and IP video network.
Other IP telephone networks include, for example, an “IP data multicast network” that transfers IP data such as electronic books and electronic newspapers from one sending source to a plurality of destinations, and an “IP-based TV broadcast network,” an IP audio-visual network, which transfers (or broadcasts) both TV's voice data and video data to a plurality of destinations using multicast technology, one of technologies. These multicast type network differ from the preceding IP telephone networks in that they do not employ the one-to-one communication scheme.
As shown in FIG. 1, in the conventional IP network 20 as represented by the Internet, an IP packet 26-1, including IP telephone data, IP video data and IP electronic voucher text data, is dispatched from a terminal 23-1 within a LAN 21 to a terminal 23-2 in a LAN 22 through a router 24-1 in the LAN 21 and routers 22-1 to 22-4 in the IP network 20 and through a router 24-2 in a LAN 22. The Internet, while it cannot guarantee the communication speed and others during the IP transfer, is generally called a “best effort network” in the sense that it makes the best effort. The IP telephone data, the IP video data and the IP electronic voucher text data flow in an intermingled manner through the communication circuits in the IP network 20, as in this example. That is, the conventional IP networks do not contain therein a plurality of separated IP networks with various characteristics, such as the IP telephone network and IP video network, the IP electronic text network, the best effort network, the IP data multicast network and the IP-based TV broadcast network. For this reason and others, the IP telephone network, IP video network, IP electronic text network, best effort network, IP data multicast network and IP-based TV broadcast network have been constructed separately, giving rise to a problem of an increased overall cost of the entire IP network.
By referring to FIG. 2 a multicast type IP network 27-1 that transfers data from one originating source to multiple destinations will be explained. Reference numbers 27-2 to 27-9 represent routers, of which 27-2, 27-6, 27-7, 27-8 and 27-9 in particular are routers to which the users' IP terminals 28-1 to 28-9 can connect via communication circuits and which are also called network nodes. The routers 27-3, 27-4, 27-6, 27-7, 27-8 have a multicast-by-router table that tells each router to send a received IP packet to a plurality of communication circuits according to a multicast address contained in the received IP packet. In this embodiment, the multicast address specifies “MA1”. The IP terminal 28-1 sends an IP packet 29-1 which has a multicast address “MA1” through the router 27-2. When it reaches the router 27-3, the router 27-3 copies the IP packet 29-2, checks the multicast-by-router table and transfers IP packet 29-3 and IP packet 29-4 onto communication circuits. The router 27-4 copies the received IP packet 29-3 and, according to the multicast-by-router table, transfers IP packet 29-5 and IP packet 29-6 onto communication circuits. The router 27-5 has no multicast-by-router table and so the IP packet 29-4 passes through the router 27-5 to be transferred as IP packet 29-7 to the router 27-8. The router 27-6 copies the received IP packet 29-5, checks the multicast-by-router table and transfers IP packet 29-8 to IP terminal 28-2 and IP packet 29-9 to IP terminal 28-3. The router 27-7 copies the received IP packet 29-6, references the multicast-by-router table and transfers IP packet 29-10 to IP terminal 28-4 and IP packet 29-11 to IP terminal 28-5. The router 27-8 copies the received IP packet 29-7, references the multicast-by-router table and sends the IP packet 29-12 to IP terminal 28-6, IP packet 29-13 to IP terminal 28-7 and IP packet 29-14 to IP terminal 28-8. When the source terminal 28-1 sends electronic books and electronic newspapers in a digital data format to the IP network 27-1, the IP network 27-1 functions as an IP data multicast network for distributing electronic books and electronic newspapers, with the IP terminals 28-2 to 28-8 representing IP terminals of the users purchasing the electronic books and electronic newspapers. When the source terminal 28-1 is replaced with a TV broadcast audio-visual transmission equipment and a TV program (i.e., voice and video) is broadcast, this IP network works as an IP-based TV broadcast network, with IP terminals 28-2 to 28-8 representing TV viewers' IP terminals with TV reception function.